1. Field of the Invention
The invention relates to techniques of generating an acceleration profile of a controlled object, and more particularly to techniques of generating an acceleration profile for allowing a velocity and/or a position of a controlled object to be controlled so as to achieve a target velocity and/or a target position with enhanced accuracy.
2. Description of the Related Art
A bang-bang control algorithm is known as a conventional control algorithm for controlling a velocity and/or a position of a controlled object (e.g., a moving object, a rotating object, etc.) to achieve a target velocity and/or a target position.
FIG. 12 explains the process of generating a target velocity profile of a controlled object by the use of a conventional bang-bang control algorithm.
More specifically, FIG. 12(a) graphs an acceleration profile indicative of a time history of an acceleration of the controlled object, and FIG. 12(b) graphs a target velocity profile indicative of a time history of a velocity of the controlled object, which profile is generated based on the acceleration profile shown in FIG. 12(a).
FIG. 12(c) illustrates a table storing therein various parameters (tuning parameters or profile parameters) which cooperate to define a desired acceleration profile.
The various parameters include the duration T1 (=100 msec) of an acceleration phase, the duration T2 (=100 msec) of a constant-velocity phase, the duration T3 (=100 msec) of a deceleration phase, and a constant velocity V (=15 inch/sec) during the constant velocity phase, all of which have been stored in the table shown in FIG. 12(c).
In an example where a conventional bang-bang control is performed, for the creation of the target velocity profile shown in FIG. 12(b), the acceleration profile shaped as a square waveform as shown in FIG. 12(a) is first generated using the various parameters stored in the table shown in FIG. 12(c).
The target velocity profile shown in FIG. 12(b) is generated by integrating accelerations of the controlled object occurring in accordance with the acceleration profile shown in FIG. 12(a).
It is added that a target position profile indicative of a time history of a position of the controlled object can be generated by integrating velocities of the controlled object occurring in accordance with the target velocity profile shown in FIG. 12(b).
Japanese Patent Application Publication No. HEI 11-353029 discloses a conventional control algorithm for controlling the velocity of a controlled object to achieve its target velocity.
This algorithm, constructed by focusing on the torque of a motor which is an example of a drive source for driving a controlled object, allows a target velocity profile during an acceleration phase to be generated to have a shape formed by combining a constant-acceleration portion and an exponential acceleration portion.
During the constant-acceleration portion, a target velocity increases over time from a start point of acceleration, so as to be graphically represented by a straight line.
On the other hand, during the exponential acceleration portion, the target velocity increases over time exponentially, before reaching a constant-velocity phase which follows the acceleration phase.